Large private networks are difficult to secure because of their vulnerability to attacks. One type of attack, a cyber attack, includes an attack by cyber attackers who gain access to the private network from outside of the private network using a public network (e.g., the Internet), for example. Another type of attack includes an inside attack which involves cyber attackers directly connected to the private network. In general, cyber attackers take advantage of vulnerabilities in network protocols and in systems such as servers, desktops, routers, gateways, firewalls and so forth.
In order to prevent these attacks, analysis is performed to determine a network's vulnerabilities so that weaknesses may be addressed. However, analysis of cyber attacks may be difficult because compromising one device in a network often provides a stepping-stone that may be used to launch further attacks. For example, a cyber attacker may jump from one device to another device, eventually achieving one or more goals (e.g., compromising an e-mail server). One type of analysis for security assessment is to determine the level of compromise possible for hosts in a network from a given attacker starting location. One type of analysis tool used in this security assessment is an attack graph.